Optical pickup actuator

ABSTRACT

There is provided an optical pickup actuator for actuating a lens holder having an object lens according to an interaction between coils and magnets. The optical pickup actuator includes a lens-seating portion formed on the lens holder to support the object lens and a lens guide portion protruding from the lens-seating portion to securely support the object lens. The lens guide portion has an adhesive confining groove in which adhesive can be injected to securely fix the object lens.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/311,342, filed on Dec. 20, 2005, entitled “OPTICAL PICKUP ACTUATOR”,the entirety of which is incorporated herein by reference

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical pickup actuator for readingand writing data from and to an optical recording medium.

2. Description of the Related Art

The optical pickup actuator maintains a relative location between anobject lens and an optical recording medium at a predetermined distanceby moving a moving part on which the object lens is mounted and readsand writes information from and to the optical recording medium byfollowing a track of the optical recording medium.

The optical pickup actuator has a permanent magnet and a coil. When theelectric current is applied to the coil, the optical pickup actuatormoves the object lens to a desired location. At this point, the movingpart moves in focusing and tracking directions that are perpendicular toeach other.

FIGS. 1A and 1B are schematic views of an optical pickup actuatoraccording to the related art.

Referring to FIGS. 1A and 1B, an optical pickup actuator includes a lensholder 102 for mounting an object lens on a central portion thereof andhaving an outer circumference around which tracking and focusing coils106 and 105 are wound, magnets and yokes 103 and 104 installed on thebase and opposing the tracking and focusing coils 106 and 105 of thelens holder 102, a plurality of wire suspensions 107 each having a firstend fixed on a side surface of the lens holder to support the lensholder 102, and a damper holder 109 to which a second end of each wiresuspensions 107 is fixed.

Reference numeral 109 denotes fixing plates fixed on the lens holder 102and the first ends of the wire suspensions 107 are fixed on the fixingplates 109 through a soldering process.

The optical pickup actuator will be now described in more detail.

The object lens 101 is mounted on the central portion of the lens holder102. The focusing coil 105 for focusing is wound around each corner ofthe lens holder. The tracking coil for tracking is wound around a centerportion of left and right surfaces of the lens holder 102.

The yokes 104 are formed of a ferromagnetism material protrude. Theyokes face the focusing and tracking coils 105 and 106. The magnets arefixed on front surfaces of the respective yokes 104. The yokes 104 arefixed on a pickup base (not shown).

The fixing plates 108 are couple to the lens holder 102. The first endsof a pair of wire suspensions 107 parallel to each other are fixed toeach fixing plate 108 through the soldering process. The second ends ofthe wire suspensions are fixedly inserted in a damper of the damperholder 109.

The damper is coupled inside the damper holder 109 so that the wiresuspensions each having a rigidity can has a damping property. A mainboard (not shown) is coupled to an outer surface of the damper holder109. The second ends of the wire suspensions 107 are actually fixed onthe main board.

The lens holder 102 is lifted by the wire suspensions 107 and electriccurrent is applied to the wire suspensions 107.

When electric current is applied to the tracking coil 106, repulsive andattractive forces are generated by an electromagnetic force between thefocusing coil 105 and the magnets 103. By the repulsive and attractiveforces, the lens holder 102 moves in the focusing direction (in avertical direction), thereby operating a focusing servo for compensatingfor a focusing error.

The above-described optical pickup actuator is a moving coil type wherethe focusing and tracking coils 105 and 106 move together with the lensholder 102 around which the focusing and tracking coils 105 and 16 arewound.

There is also a moving magnet type where the magnets are attached on theouter circumference of the lens holder so as to move together with thelens holder. At this point, the movement using the magnets and the coilsuses Lorentz's force of Fleming's left-hand rule.

The above-described optical pickup actuator reads and writes informationon an optical recording medium. In recent years, as multimedia systemshave been rapidly developed and capacities of multimedia contents suchas games and movies has been increased, it has been required that theoptical pickup actuator must be reliable to stably drive the multimediasystems for many hours.

When the multimedia system is driven for many hours, heat is generatedby the electric current applied to the coils of the optical pickupactuator and transmitted to the object lens through the lens holder.

When the heat generated by the coils is transmitted to the object lensfor a long time, the aberration is increased. Furthermore, whenexcessive electric current is applied to the coils, the object lens maybe cracked due to a thermal-stress. Therefore, there is a need for anoptical pickup actuator that can improve a driving reliability byreducing the heat transmitted from the coils to the object lens.

Also, in a high speed optical pickup actuator, even when the object lensis attached to the lens holder using adhesive, the lens holder may bedifferent in a frequency response from the object lens since theadhesive force is not enough. That is, a resonance peak of the lensholder may be greater than a resonance peak of the object lens.

Therefore, there is also a need for an optical pickup actuator that canimprove the driving reliability by attenuating the resonancecharacteristics.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an optical lensactuator that substantially obviates one or more problems due tolimitations and disadvantages of the related art.

An object of the present invention is to provide an optical pickupactuator that can minimize the transmission of heat from coils to anobject lens by forming recessed portions on side surfaces of a lensholder.

Another object of the present invention is to provide an optical pickupactuator that can block out heat that is transmitted from coils to anobject lens by processing heat discharge grooves on a lens-seatingportion surrounding a beam-passing hole.

Still another object of the present invention is to provide an opticalpickup actuator that can enhance a bonding force of an object lens byimproving a bonding structure between a lens holder and the object lens.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein,there is provided an optical pickup actuator for actuating a lens holderhaving an object lens according to an interaction between coils andmagnets, the optical pickup actuator including: a lens-seating portionformed on the lens holder to support the object lens; and a lens guideportion protruding from the lens-seating portion to securely support theobject lens, wherein the lens guide portion has an adhesive confininggroove in which adhesive can be injected to securely fix the objectlens.

In another aspect of the present invention, there is provided an opticalpickup actuator for actuating a lens holder having an object lensaccording to an interaction between coils and magnets, the opticalpickup actuator, wherein the lens holder is provided at a side surfacewith a dissipation groove that does not directly contact a trackingcoil.

In still another aspect of the present invention, there is provided anoptical pickup actuator comprising: a lens holder having a lens-seatingportion on which an object lens seats and a bobbin around which afocusing coil is wound, and a coil-supporting portion around which atracking coil is wound, wherein the coil-supporting portion protrudesfrom a side surface of the lens holder and the side surface of the lensholder is provided with a coil-contacting portion contacting thetracking coil and a heat dissipation groove that does not contact thetracking coil.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIGS. 1A and 1B are schematic views of an optical pickup actuatoraccording to the related art; and

FIGS. 2 through 4 are views illustrating an optical pickup actuatoraccording to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

FIGS. 2 through 4 are views illustrating an optical pickup actuatoraccording to an embodiment of the present invention.

Referring to FIGS. 2 through 4, a lens holder 202 has first heatdissipation grooves 204 formed on a lens-seating portion 209 on which anobject lens 201 seats, second heat dissipation grooves 225 formed oncenters of opposite side surfaces of the lens holder 202, and third heatdissipation grooves 232 formed on left and right portions of each of theopposite side surfaces of the lens holder 202.

The object lens 201 seating on the lens-seating portion 209 is alignedwith a beam-passing hole 203 surrounded by the lens-seating portion 209.Lens guide portions 211 protrude from the lens-seating portion 209 tofixedly support the object lens 201. The lens guide portions 211 areformed along a circumference having an inner diameter greater than anouter diameter of the object lens 201.

The lens guide portions 211 are opened upward and toward a locationwhere the object lens is located. For example, the lens guide portions211 may be disposed about 90° apart. Each of the lens guide portion 211has an adhesive confining groove 212 and an adhesive reinforcingprojection 213 for dividing the adhesive confining groove 212 into twosections. The adhesive reinforcing projection 213 extends toward theobject lens.

One or more reinforcing projections 213 may be formed on each lens guideportion 211, having a height lower than that of the lens guide portion211.

Referring to FIG. 4, the adhesive is injected into the lens guideportion 211 after the object lens 201 seats on the lens-seating portion209. The adhesive may be a UV adhesive or a bond. The injected adhesivedoes not leak out of the lens guide portion 211 due to the internalstructure of the lens guide portion 211. At this point, since theadhesive reinforcing projection 213 is formed in the adhesive confininggroove 212, the adhesive force of the adhesive can be more enhanced.

As the adhesive is applied between he lens guide portions 211 and theobject lens 201, the adhesive force for bonding the object lens 201 tothe lens holder 202 is further enhanced.

Accordingly, when the lens holder 202 is driven at a high speed, theresonance peak of the object lens 201 becomes identical to that of thelens holder 202.

Meanwhile, the first heat dissipation grooves 204 are respectivelyformed on opposite portion of the lens-seating portion 209 that areadjacent to the coils. By the first heat dissipation grooves 204,portions of the object lens 201 do not contact the lens-seating portion209.

Therefore, an amount of the heat transmitted to the object lens 201through the lens-seating portion 209 can be reduced.

Also, second heat dissipation means is formed on the centers of theopposite surfaces of the lens holder 200. The second heat dissipationmeans includes second coil contacting portions 223 and 224 on whichportions where coil-supporting portions 221 and 222 will be formed areelevated so that upper and lower portions of the tracking coils 206contact the coil supporting portions 221. The second heat dissipationmeans further includes the second dissipation grooves 225 formedportions where a middle portion of an inner surface of the tracking coil206 will contact. By the second dissipation grooves 225, portions of thetracking coil 206 do not contact the lens holder 202.

Here, each of the second heat dissipation grooves 225 may be unevenlyformed and has a width wider than those of the second coil contactingportions 223 and 224.

Also, third heat dissipation means is formed by stepping left and rightsides of opposite surface of the lens holder 202, which corresponds toinner surfaces of bobbins 230 around which the focusing coil 205 iswound. The third heat dissipation means includes third contactingportions 231 to which upper and lower portions of the focusing coil 205contact. The third contacting portions 231 are elevated from theopposing surfaces of the lens holder 202. The third heat dissipationmeans further includes third heat dissipation grooves 232 formed on theopposite surface of the lens holder 202. The third heat dissipationgrooves 232 correspond to the middle portion of the focusing coil 205.Therefore, the middle portion of the focusing coil does not directlycontact the lens holder 202 by the third dissipation grooves 232.

Each of the third heat dissipation grooves 225 may be unevenly formedand has a width defined between the upper and lower bobbins 230.Preferably, the width of the third heat dissipation grooves 225 is widerthan those of the third coil contacting portions 231.

The case where the coils are wound around the lens holder 202 having theabove described first and second heat dissipation means is illustratedin FIG. 3.

The coils may be formed in a variety of shapes such as a rectangularshape or a trapezoid shape.

Referring to FIG. 3, the tracking coils 206 are wound around middleportions of the opposite surfaces of the lens holder 202 and thefocusing and radial coils 205 and 207 are wound around left and rightsides of the opposite surfaces of the lens holder 202. The trackingcoils 206 are supported by the coil supporting portions 221 and 222 andthe middle portion of the inner surfaces of the tracking coils 206 arespaced away from the opposite surfaces of the lens holder 202 by thesecond heat dissipation grooves 225. That is, since the upper and lowerportions of the inner surfaces of the tracking coils 206 contact thesecond coil contacting portions 223 and 224, the middle portions of theinner surfaces of the tracking coils 206 do not directly contact thelens holder 202 by the second dissipation grooves 225. Accordingly, anamount of the heat generated by the tracking coils 206 and transmittedto the object lens can be reduced.

Furthermore, the focusing and radial coils 205 and 207 are dually wound.Middle portions of the inner surfaces of the focusing and radial coils205 and 207 do not directly contact the tracking coil 206 by the thirdheat dissipation grooves 232 stepped inward from the third coilcontacting portions 131. Therefore, an amount of heat generated from thefocusing and radial coils 205 and 207 and transmitted to the object lenscan be reduced.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present invention. Thus,it is intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. Optical pickup apparatus, comprising: a lens holder having an objectlens; and a lens-seating portion formed on the lens holder to supportthe object lens, wherein the lens-seating portion has a heat dissipationgroove that does not directly contact the object lens.
 2. The opticalpickup apparatus according to claim 1, further comprising a lens guideportion having an adhesive confining groove in which adhesive can beinjected to securely fix the object lens.
 3. The optical pickupapparatus according to claim 2, wherein the lens guide portion is openedupward and toward the object lens so that the adhesive can be injectedin a space defined between an inner surface of the lens guide portionand the object lens.
 4. The optical pickup apparatus according to claim2, wherein the lens guide portion has an adhesive reinforcing projectiondividing the adhesive confining groove into two sections.
 5. The opticalpickup apparatus according to claim 2, further comprising one or moreadditional lens guide portions.
 6. Optical pickup apparatus, comprising:a lens holder that holds an object lens; and a lens-seating portion onwhich an object lens seats having at least one heat dissipation groovethat does not directly contact the object lens.
 7. The optical pickupapparatus according to claim 6, wherein the lens holder is furtherprovided at the side surface with a heat dissipation groove that doesnot directly contact a focusing coil.
 8. The optical pickup apparatusaccording to claim 6, wherein the lens holder is further provided at theside surface with a heat dissipation groove that does not directlycontact a radial coil.
 9. The optical pickup apparatus according toclaim 6, further comprising: a lens guide portion formed on thelens-seating portion to support the object lens and an adhesiveconfining groove for confining adhesive for securely fixing the objectlens to the lens guide portion.
 10. The optical pickup apparatusaccording to claim 9, wherein the lens guide portion includes anadhesive reinforcing protrusion for dividing the adhesive confininggroove into at least two sections.
 11. An optical pickup actuator,comprising: a lens holder including a lens-seating portion to support aobject lens; and a lens guide portion protruding from the lens-seatingportion to securely support the object lens having: at least oneadhesive confining groove configured to receive an injection of adhesiveto securely fix the object lens; and an adhesive reinforcing projectiondividing the at least one adhesive confining groove into at least twosections.
 12. The optical pickup actuator according to claim 11, furthercomprising: a radial coil wound around a bobbin.
 13. The optical pickupactuator according to claim 11, wherein the lens guide portion is openedupward and toward the object lens so that the adhesive can be injectedin a space defined between an inner surface of the lens guide portionand the object lens.
 14. The optical pickup actuator according to claim11, further comprising one of more additional lens guide portions. 15.An optical pickup actuator, comprising: a lens holder including alens-seating portion to support a object lens; and a lens guide portionprotruding from the lens-seating portion to securely support the objectlens, the lens guide portion having at least one adhesive confininggroove divided into at least two sections.
 16. The optical pickupactuator according to claim 15, wherein the lens guide portion is openedupward and toward the object lens so that the adhesive can be injectedin a space defined between an inner surface of the lens guide portionand the object lens.
 17. The optical pickup actuator according to claim15, further comprising one of more additional lens guide portions. 18.Optical pickup apparatus, comprising: means for holding a lens includingan object lens; and means for seating the object lens of the means forholding, wherein the means for seating the object lens has a heatdissipation groove that does not directly contact the object lens. 19.The optical pickup apparatus according to claim 18, further comprising:means for guiding a lens having means for confining an adhesive in whichadhesive can be injected to secure the object lens.
 20. The opticalpickup apparatus according to claim 19, wherein the means for guidingthe lens includes means for dividing the means for confining an adhesiveinto at least two sections.